The simplest form of base isolation uses flexible pads between the base of the building and the ground. When the ground shakes, inertia holds the building nearly stationary while the ground below oscillates in large vibrations. Thus, no force is transferred to the building due to the shaking of the ground. The flexible pads are called base-isolators and structures using these devices are called base-isolated buildings. Through the activities described, students can investigate how buildings with base isolation can withstand violent ground shaking while other buildings that are rigidly connected to the ground may sustain considerable damage during earthquake shaking.